Public and Authenticated App with Authorization Scheme once per session

Question

I have a question . . .
Let's say I have an application and at the application level I have an authorization scheme (auth1). If auth1 is set up to evaluate once per session, does it authenticate for the public user, then pass me back to the page and then check then evaluate the auth1 scheme. Or does it evaluate the auth1 scheme, then log in, then return to the page. Is it the same regardless of authentication scheme (e.g. Oracle SSO).
It may make a big difference. If the authorization sheme is based upon the user (most will be) then setting it to evaluate once per session can be a real problem. If it evaluates before the user logs in, then it won't really work.
This is an even bigger question when the application does not have a authorization scheme at the application level and allows public pages. If a page that is not public has an authorization scheme set, and the user goes directly to that page, it seems to authenticate the authorization scheme and then logs you in, but does not re-evaluate authorization scheme after you are logged in. Is this accurate? I realize that I could set it up to evaluate for every page view, but I really only need it once after login.
Is this clear?

Answer 1

Anton,
It seems that all authorization schemes that are set to evaluate once per session are evaluated with the beginning establishment of a session.Sort of correct. Authorization schemes don't get evaluated until the component that uses them is considered for rendering or processing. So if the authorization scheme is attached to a page, it won't fire until the page is requested. If another component uses that scheme first, the evaluation will happen then and will not happen again during the session.
What if I have another page that is not public. If it is the first page I go to, what happens. Obviously, I get redirected to login, then login. Do the authorization schemes get evaluated at this point?Yes, assuming the authorization scheme is used by the page, the scheme is evaluated during the first rendering or processing of the page in the session, after the authentication step.
Now, what if I have a page that is public, but also has an auth scheme (odd, but could happen). Now what happens, does the auth scheme get evaluated before or after login?During the rendering or processing of the page after the authentication step. For a public page, the authentication step is performed up to the point where it determines that no authentication is required.
OK, now let's add in Application level auth scheme. I can have public or private pages. If I go to a private page, when does the app level auth scheme kick in? How about for a public page?When an application uses an authorization scheme, it gets evaluated before the authorization scheme (if any) for the page that is being requested, so the public/private property of the page doesn't matter.
General advice: when an authorization scheme uses :APP_USER, it doesn't work well to have it fire once per session because it'll get run before authentication to the application occurs, which sets APP_USER. You can have such schemes fire once per page view and for PL/SQL function-type schemes, have them give a "pass" when the current page is the login page, that kind of thing.
In addition, if the overhead of running a scheme is high, one can set an application-level item to indicate that a once-per-page scheme has already run satisfactorily. The PL/SQL-type schemes can access the value of such an item to skip the expensive part of the evaluation and return true immediately.
Finally, the htmldb_application.reset_security_check API can be called in order to reset the "fired" status of all authorization schemes in the session, allowing them to be re-evaluated if/when they are encountered again in the session.
Hope this helps,
Scott